define(function(require, exports, module){

    require.async('./module3', function(m3){
        console.log('异步引入模块3：' + m3.API_KEY);
    });
    
    var module2 = require('./module2');
    function show(){
        console.log('模块4：' + module2.msg);
    }

    exports.show = show;
});